The present invention relates generally to soil stabilizer machines. More particularly, the present invention relates to a soil stabilizer machine with a recycler screen for assuring that the output from the machine is properly sized.
Self propelled soil stabilizer machines which employ a horizontal rotor surrounded by a housing for comminuting and/or mixing soil and other material over which the machine passes are known. The soil stabilizer machine have found wide applications for many purposes. The machine may be used to dig up and comminute old asphalt paving which is reapplied to the ground to form a suitable foundation for subsequent operations. Further, the soil stabilizer machine may be used to blend or mix the soil with suitable additives, such as cement to produce "soil cement" or lime, depending upon the desired use of the processed material.
However, if the ground or material over which the machine passes is heavily packed or contains relatively large rocks, blades arranged on the horizontal rotor do not sufficiently break up the material within the housing in a single pass. For certain applications of a soil stabilizer machine, it is essential that the ground or material be broken up into a sufficiently small particle size for the intended use of the processed ground. In some prior art soil stabilizer machines the only way to obtain a desired particle size was to pass over the same ground numerous times with the soil stabilizer machine. This procedure is particularly time consuming and still does not ensure that the desired particle size will be obtained.
An apparatus has been proposed in an attempt to control the particle size of cultivated soil. A tiltable cutting edge located on a lower surface of a cultivating machine digs up soil and delivers the soil to a chain belt which moves the material in an arcuate path. The chain belt directs material against a grid comprised of a plurality of rods and cross bars which direct material back to a lower portion of the chain belt if the material is to large to pass through the openings in the grid. The motion of the material between the grid and the chain belt causes lumps of earthy material to be broken up into smaller particles that will pass through the openings in the grid. Eventually, the area between the chain belt and the grid becomes filled with large rocks which cannot be broken up and accordingly the machine must be stopped so that the area may be emptied. A device of this general type is disclosed in U.S. Pat. No. 4,005,755 issued Feb. 1, 1977 to Bakke et al.
A further earth preparing apparatus for separating rocks from soil includes a rotatable tilling apparatus for digging into the earth in essentially a plurality of furrows. Quantities of earth are thrown backward relative to the direction of motion of the apparatus against a screen. The screen is inclined away from the rotatable tilling apparatus such that small particles of soil pass through the screen while rocks and clumps of earth which are to large to pass through the screen drop into one of the furrows or channels which have been created by the rotary tilling apparatus. These rocks and large clumps of earth are subsequently covered by soil which passes through the screen. In other words, a device of this type merely places a layer of fine soil on top of the rocks and large clumps which were present initially. A device of this general type is disclosed in U.S. Pat. No. 3,563,191 issued Feb. 16, 1971 to Yovanovich.
Other soil stabilizing or cultivating apparatus are disclosed in U.S. Pat. Nos. 3,532,169 issued Oct. 6, 1970 to van der Lely; 3,584,406 issued June 15, 1971 to Kershaw; 3,995,570 issued Dec. 7, 1976 to van der Lely; 4,151,883 issued May 1, 1979 to van der Lely et al; and 4,214,633 issued July 29, 1980 to Jackson et al. None of these patents discloses an apparatus for recycling large particles of materials dug up by a soil cultivator or for assuring that a uniform particle size of the output is obtained.
Various objects and advantages will be evident to those of ordinary skill from the following description of a preferred embodiment of a soil stabilizer machine according to the present invention. A soil working or stabilizer machine according to the present invention includes a generally cylindrical rotor having a plurality of teeth arranged along the cylindrical surface of the rotor. The rotor is driven by a suitable motor about a horizontal axis for digging and for comminuting or pulverizing soil. A housing surrounds the rotor for confining the soil dug by the rotor for comminution or mixing by the rotor. According to the present invention, a recycler screen is provided behind the rotor with respect to the direction of travel of the soil working machine. The recycler screen selectively permits particles of soil of less than a predetermined size to be dispensed onto the ground behind the rotor and selectively returns particles of soil or rock greater than the predetermined size to the rotor to be further comminuted by the rotor. In the preferred embodiment, the screen is arranged at a rear of the housing generally parallel to the rotor axis such that a lower edge of the screen is arranged closer to the periphery of the rotor than an upper edge of the screen. This arrangement ensures that the particles which do not pass through the screen will be directed back toward the rotor to be broken into smaller particles within the housing.
Further, according to the preferred embodiment, the screen is pivotably mounted about an upper edge of the screen for movement between a first position for sizing the particles and a second, storage position. In the storage position, the screen does not interfere with the dispensing of soil onto the ground behind the rotor. The screen preferably comprises a rigid generally rectangular frame having a plurality of horizontal and vertical rod members secured to the frame and woven together to form openings of a predetermined size through which particles of material must pass. A plurality of vertical reinforcing members arranged on a side of the screen remote from the rotor are provided to reinforce the rods of the screen to limit bending of the rods caused by rocks and material hurled at the screen during machine operation. Still further, suitable arrangements for securely fastening the screen in the first and second positions are provided.
The present invention provides a simple and effective apparatus for ensuring that the particles dispensed behind the rotor are properly sized for the particular purpose for the processed material. In addition, the present invention provides a screen which can be readily moved to a storage position so that particles of any size may be dispensed behind the rotor.